Name already defined error when using `property.setter` on a property declared with function-based syntax

Bug Report

When using function-based syntax to declare property (i.e. foo = property(get_foo)), mypy reports a "Name already defined" error when trying to reassign to it using property.setter (see below)

To Reproduce

1. Save this code to a python file:

class X:
    def __init__(self):
        self._foo = 123

    def get_foo(self) -> int:
        return self._foo

    foo = property(get_foo)

    @foo.setter
    def foo(self, value: int) -> None:
        self._foo = value

2. Run mypy on it
3. See output.

Expected Behavior
No errors. I think this should apply not just to properties but also to any other custom descriptors.

Actual Behavior
I got an error

main.py:10: error: Name "foo" already defined on line 8
Found 1 error in 1 file (checked 1 source file)

Your Environment

• Mypy version used: both 0.910 and latest
• Mypy command-line flags: None
• Mypy configuration options from mypy.ini (and other config files): None
• Python version used: 3.9

Start with the reported Python reproducer and run mypy to confirm the "Name already defined" diagnostic. Trace how function-based properties and the @foo.setter reassignment are analyzed, including whether custom descriptors follow the same path; done means the reproducer and equivalent descriptor cases type-check without the duplicate-name error.